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What Batted Ball Data Tells Us About Matt Carpenter’s Struggles

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MLB: Kansas City Royals at St. Louis Cardinals Joe Puetz-USA TODAY Sports

With Matt Carpenter this season, two things are true - He is hitting the ball hard, and he is struggling at the plate. Matt Carpenter’s 87 wRC+ in 2021 is the worst of his career, excluding the shortened 2020 season (84 wRC+). The infielder’s 91.3 mph average exit velocity is also the highest of his career since Baseball Savant began tracking in 2015. This is an improvement of over 3 miles per hour from last season, but yet it has not led to a marked improvement in production.

Carpenter’s xwOBA (.356) is significantly higher than his wOBA (.298) and his xwOBACON (.457) is more than 100 points higher than his wOBACON (.346). Thus, it is certainly possible, and even likely, that Carpenter has been unlucky at the plate. However, it is not just bad luck that is causing him to struggle despite hitting the ball hard.

The calculation of xwOBA takes into account a batted ball’s exit velocity and launch angle (and occasionally sprint speed) in order to create an expected outcome. Since Carpenter has such a high exit velocity and plenty of fly balls, it makes sense that his xwOBA is high. Despite this, batted ball data gives an explanation as to why many of Carpenter’s hard hit balls have not become hits.

To begin with, Carpenter has hit just 7.1% of his ground balls to the opposite field. 75% of his ground balls have been pulled with another 17.9% hit up the middle. This is certainly not ideal since teams have shifted on Carpenter in 92.4% of his plate appearances. Because of this, the 35-year-old is hitting most of his groundballs at the most crowded part of the infield. As a result, Carpenter has a wOBA of just .084 on pulled ground balls this season. This explains why he has a wOBA of just .126 on ground balls in 2021.

This lack of success on ground balls for Carpenter has been fairly consistent throughout his career, although this season has been especially bad. While Carpenter has not posted a wOBA above .200 on ground balls since 2018, his .126 wOBA this season is worst of his career. Some of this is likely due to bad luck as his wOBA could be closer to the mid-to-upper .100s considering his exit velocities. However, hard hit balls can be effectively neutralized by the shift, and that is what is happening to Carpenter.

Ground balls are simply part of the equation for Carpenter, though, and a minor part of it as well. Fly balls and line drives are where most of Carpenter’s production comes from. The problem for Carpenter this year has been that his wOBA on fly balls is down to just .294, the lowest mark of his career since 2014. Another issue for Carpenter is that his line drive rate has dropped to 23.3% (according to Baseball Savant), which is the lowest rate of his career. Fangraphs disagrees, and gives him a 25% line drive rate, which is just under his career average, so this is not the main issue. A large amount of Carpenter’s production does come on line drives, though, so a small change is certainly enough to effect his stats.

The decrease in production on fly balls is almost certainly due to where Carpenter has hit his fly balls this season. He has pulled just 16% of his fly balls this season, while 52% of them have been hit to center (the longest part of the park), and 32% of them have gone to the opposite field. This season, Carpenter has a whopping 1.067 wOBA on pulled fly balls, including all three of his home runs.

On fly balls to center, the veteran has posted just a .190 wOBA. This drops to .078 on fly balls to the opposite field. Traditionally, Carpenter has had almost no success on opposite field fly balls while fly balls to center have been more of a mixed bag. The bulk of Carpenter’s fly ball success has always come on the pull side. As a result, it is not good that Carpenter is currently posting the lowest pulled fly ball rate of his career since 2015.

Obviously, harder hit balls tend to fall for hits more often than more weakly hit balls, with all things being equal. The shift can change that when it comes to ground balls, and this has certainly been the case with Carpenter as he is hitting balls hard, but most of his ground balls go into the shift. A drop in line drive rate, coupled with fly balls that are primarily hit up the middle or to the opposite field, has also led to a poor statistical season for Carpenter, even though his exit velocity is the highest of his career.

Bad luck is almost certainly playing a part, but batted ball distribution is likely playing a larger role. If the veteran can hit more opposite field ground balls and pulled fly balls, then he will be able to hit the ball where the defense is not playing and use his power more fully. Down the stretch, this could help Carpenter as his time with the St. Louis Cardinals winds down.